A transmission/reception system which transmits image data for displaying an image on an image display device such as a liquid crystal display device is disclosed in Patent Literature 1. The transmission/reception system 2 disclosed in this literature includes a transmission device 10A which transmits image data and a reception device 20A which receives the image data transmitted from the transmission device 10A and causes the image display device to display the image as illustrated in FIG. 1.
The transmission device 10A includes a serializer 11 and an encoding unit 12. The encoding unit 12 encodes image data (parallel data) to be transmitted. The serializer 11 converts the encoded parallel data into serial data and transmits serial data in which the clock is embedded to the reception device 20A.
The reception device 20A which receives data transmitted from the transmission device 10A includes a deserializer 21 and a decoding unit 22. The deserializer 21 recovers serial data and a clock on the basis of the received data and converts the serial data into parallel data. The decoding unit 22 reproduces image data by decoding the parallel data. Technology for recovering serial data and a clock on the basis of the received data in the reception device is referred to as CDR (clock data recovery).
Compared to transmission of parallel data, a transmission/reception system which adopts this CDR technology to transmit serial data can further reduce the number of transmission paths for data transmission and further reduce an area of a substrate connected to the transmission path. Also, this transmission/reception system can eliminate a problem of skew between data and a clock in principle and transmit high-speed and large-volume data because data in which a clock is embedded is transmitted.
A level of serial data to be transmitted from the transmission device to the reception device needs to transition at a high frequency in order for the data and the clock to be correctly recovered in the reception device. In order to assure high-frequency level transition in serial data to be transmitted, an encoding process is performed in the transmission device and a decoding process corresponding to the encoding process is performed in the reception device. The encoding process to be used here is, for example, an 8B10B encoding process, a scramble process, or the like.
Data (specific data) having a specific bit string for achieving synchronization of communication between the transmission device and the reception device is transmitted from the transmission device to the reception device so that the reception device correctly performs the decoding process on serial data encoded in the transmission device. In the conventional transmission/reception system, specific data is transmitted at a predetermined timing on the basis of a data enable signal (DE signal). The DE signal has a first level (e.g., H level) in a period in which valid data (image data) is transmitted and has a second level (e.g., L level) in a period in which invalid data (blanking data) is transmitted. Specific data can be transmitted at the timing of level transition of the DE signal. The specific data may be transmitted for every bit of the image data, the specific data may be transmitted for every two or more bits of the image data, and the specific data may be transmitted for every frame of the image data.